1. Technical Field
Embodiments of the invention relate to the field of desalination technology, and more particularly to an electrochemical desalination system and a method of controlling the system.
2. Discussion of Related Art
One type of electrochemical desalination system utilizes at least a pair of electrodes within an electrolyte solution. The electrochemical desalination system comprises a plurality of successive operation cycles, and each operation cycle comprises a charging mode of operation and a discharging mode of operation. In the charging mode of operation of the electrochemical desalination system, the pair of electrodes is oppositely charged by an external power supply to form an electric field between the pair of electrodes. Ions in the electrolyte solution are driven by the electric field toward the oppositely charged electrodes and adsorbed on surfaces of the electrodes. Accordingly, the pair of electrodes forms a capacitor which stores electric energy during the charging mode of operation. During the charging mode of operations, the concentration of the ions in the electrolyte solution reduces over time, and accordingly the electrolyte solution exiting from the electrochemical desalination system is a dilute water with reduced ions as compared to the electrolyte solution fed into the electrochemical desalination system. During the discharging mode of operation, the electric energy stored in the capacitor (electrodes) is released, and ions desorb from the surfaces of the pair of electrodes into the electrolyte solution. Accordingly, the electrolyte solution exiting from the electrochemical desalination system during the discharging mode of operation is a concentrated water with a higher concentration of ions as compared to the feed solution. Such an electrochemical desalination device is also referred to as a “supercapacitor desalination (SCD) system.”
Conventional methods of discharging the pair of electrodes during the discharging mode of operations comprise forming a short circuit between the pair of electrodes, or connecting the pair of electrodes with a utility to consume the electric current released by the pair of electrodes, or reversing polarities of the pair of electrodes to release the electrical energy stored in the pair of electrodes. None of the conventional methods makes direct use of the electric energy released during the discharging mode of operation in the SCD system itself. Accordingly, it may be desirable to have an SCD system that differs from those systems or systems that are currently available and make direct use of the electrical energy released during the discharging process. It may be desirable to have a method for controlling operation of the SCD system which differs from those are currently available.